There are many (far more than the “official” estimates suggest) UK citizens living in the EU27 countries.

Two of the EU27 countries where there are significant UK populations are Spain and France. Neither of these countries require EU migrants to register, much the same as the UK which does not require EU27 citizens to register when living in the UK.

The unofficial estimates of the number of UK citizens resident in Spain & France alone is around 2 million. Whether that or the “official” figures are correct is open to debate.

The important thing is that these people, no matter how many they are, have a UK (British) passport and have the right to permanent residence in the UK. All of them have the right to stand as an MP even though some have no right to vote for one.

But it seems they all fall into the category described by Theresa May as “citizens of nowhere”.

Perhaps that justifies Theresa May ignoring not only the plight but the rights of these UK citizens.

But it’s worse than that.

Setting aside the big business interests, there are millions of people living in the UK who have a direct and personal interest in maintaining the rights and benefits they currently enjoy as EU citizens.

UK citizens who have planned, on the basis of commitments made by successive UK governments, to move to EU27 countries to mitigate the effects of one of the highest costs of living and lowest pension provisions in Europe.

Or who have, through their own initiative and skill, taken advantage of freedom of movement and rights of establishment to work or trade across the EU while resident in the UK.

There are also cross-border workers, and those who rely on the European Health Insurance Card to provide temporary health care cover while travelling in the EU27 countries, whether for business or pleasure.

To be fair, the EU hasn’t addressed these issues in its document on essential principles on citizens rights, but it has established a general principle that citizenship rights which have been exercised should be preserved. How this fares in the negotiating process has yet to be seen, but at least it gives us a jumping-off point.

Which means that currently the EU is doing more to protect the position of some categories of UK citizens than the UK government is.

To state the obvious, the question of citizenship rights is very complex, and it’s also extremely important.

While some say that the legal challenge to the government last year was purely about parliament sovereignty vs a power-grabbing executive, we have it on supremely good authority that the clinching legal argument was put forward by The People’s Challenge: only parliament can remove or modify “fundamental citizenship rights”.

This was argued by Bindmans LLP on behalf of The People’s Challenge, from the first letter through to defeating the government’s appeal in the Supreme Court.